Conventionally, a technology is known for generating a three-dimensional model by measuring the three-dimensional shape of a target object. For example, it is possible to think of a method in which a target object is placed in the center of the measurement direction (the observation direction) of a laser radar device that is capable of measuring the distance to the target object; measurement is performed by moving the laser radar device along the outer circumferential direction of the target object; and the three-dimensional shape of the target object is generated on the basis of the measurement result.
In order to obtain an accurate three-dimensional model, it is particularly important to eliminate omissions in the measurement. However, in a typical laser radar device, the laser light is deflected in a plurality of scan planes having different heights. Hence, if a target object is so thin that it is able to fit within the clearance gaps between adjacent scan planes, then that target object is not detectable by a typical laser radar device. Moreover, since the clearance gaps widen along with an increase in the distance to the target object, the number of undetectable objects also goes on increasing. Thus, in the conventional technology, that leads to omissions in the measurement of the target object for which a three-dimensional model is to be generated. For that reason, it is not possible to obtain an accurate three-dimensional  model.